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Anthophyllite

The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform

John A Hoskins – 1st expert on this subject based on the ideXlab platform

  • Anthophyllite asbestos the role of fiber width in mesothelioma induction part 4 mechanistic considerations regarding the failure to observe Anthophyllite asbestos mesotheliomas in humans
    Environment and Pollution, 2018
    Co-Authors: Edward B Ilgren, John A Hoskins

    Abstract:

    Anthophyllite is an amphibole mineral formed through a prograde metamorphism of magnesium-rich ultramafic talcose rocks through increasing pressure and temperature and dehydration. The talc and Anthophyllite are in phase equilibrium. Anthophyllite asbestos is therefore not a ‘contaminant’ of talc but a product derived from it. Fibrous talc, or so-called transitional fibers, are Anthophyllite fibers undergoing retrograde degeneration. In its fibrous asbestiform state, Anthophyllite differs in several fundamental ways from other commercially exploited forms of amphibole asbestos of which there are two broad families: monoclinic and orthorhombic. The more common forms of commercial amphibole asbestos such as crocidolite and amosite are monoclinic. The Anthophyllites are orthorhombic. The differences between the two crystal systems are reflected at the level of the basic amphibole-structure in a greater overall fiber width dimensional profile and a significant reduction in microstructural strength. Strength reduction most probably arises at the cellular level and is particularly pronounced within the thinner population of fibers. Here microstructural differences, due in significant part to stacking defects in the basic amphibole structure, can account for these observations. The lack of an observed attendant mesothelioma risk following exposure to Anthophyllite and transitional fibers in humans is a consequencel of these microstructural features that appear to differentiate them from the equidimensional monoclinic forms of amphibole asbestos such as South African crocidolite and amosite.

  • Anthophyllite asbestos the role of fiber width in mesothelioma induction part 3 studies of american and japanese Anthophyllite asbestos additional supportive evidence
    Environment and Pollution, 2018
    Co-Authors: Edward B Ilgren, John A Hoskins

    Abstract:

    The largest anthopyllite deposits in the world are found in Finland and it is from here that most of the commercial Anthophyllite derives. However, other large deposits exist in both North America and Japan. Commercial production has existed in both these countries although not on a scale which matches the Finnish mines. Small deposits are known from several other countries but, apart from minor exploitation in India no significant mining has taken place. The North American deposits are primarily in the Eastern US states, mostly Maryland, Georgia and North Carolina although there was also extensive exploration in Alabama. In Japan, the major mining site was at Matsubase on the southermost island of Kyushu. Although these mines and attendant commercial concerns operated for decades and under conditions of high dust exposure no mesothelioma clusters are known from the mining areas.

  • Anthophyllite asbestos the role of fiber width in mesothelioma induction part 2 further epidemiological studies of occupational domestic and environmental exposure to finnish Anthophyllite asbestos
    Environment and Pollution, 2018
    Co-Authors: Edward B Ilgren, John A Hoskins

    Abstract:

    Although people in all sectors of the Finnish Anthophyllite industry, including their families, have been heavily exposed to Anthophyllite there is no evidence for even a single proven case of attributable mesothelioma. A few cases have been claimed but the evidence either, that they were mesotheliomas or that amphibole exposure was solely to Anthophyllite is, in every case examined, insufficient. Even among the population who lived in Karelia in Central Finland who were exposed domestically or enviromentally to Anthophyllite released during agricultural and various domestic activities and during transport from the mines, Finnish epidemiology found no risk of mesothelioma. There is also an absence of mesotheliomas reported in the earlier Finnish literature. This anomaly compared to the effects of exposure to other amphiboles is strong support for the role of fiber width in mesothelioma production. Anthophyllite, though, is not without clinical effect. As screening techniques improved it was discovered that of every person over the age of 65 years, one third living in Karelia had bilateral pleural plaques. The area was henceforth called the Endemic Pleural Plaque (EPP) zone. Radiographic analysis of the residents living in the district of Kuusjarvi led to suggestions that the cases resulted from asbestos blown from the Paakila facility via fiber drift as far away as 30 km. Later studies showed that ‘fiber drift’ was very unlikely to be a factor in the radiological findings thus observed.

Edward B Ilgren – 2nd expert on this subject based on the ideXlab platform

  • Anthophyllite asbestos the role of fiber width in mesothelioma induction part 4 mechanistic considerations regarding the failure to observe Anthophyllite asbestos mesotheliomas in humans
    Environment and Pollution, 2018
    Co-Authors: Edward B Ilgren, John A Hoskins

    Abstract:

    Anthophyllite is an amphibole mineral formed through a prograde metamorphism of magnesium-rich ultramafic talcose rocks through increasing pressure and temperature and dehydration. The talc and Anthophyllite are in phase equilibrium. Anthophyllite asbestos is therefore not a ‘contaminant’ of talc but a product derived from it. Fibrous talc, or so-called transitional fibers, are Anthophyllite fibers undergoing retrograde degeneration. In its fibrous asbestiform state, Anthophyllite differs in several fundamental ways from other commercially exploited forms of amphibole asbestos of which there are two broad families: monoclinic and orthorhombic. The more common forms of commercial amphibole asbestos such as crocidolite and amosite are monoclinic. The Anthophyllites are orthorhombic. The differences between the two crystal systems are reflected at the level of the basic amphibole-structure in a greater overall fiber width dimensional profile and a significant reduction in microstructural strength. Strength reduction most probably arises at the cellular level and is particularly pronounced within the thinner population of fibers. Here microstructural differences, due in significant part to stacking defects in the basic amphibole structure, can account for these observations. The lack of an observed attendant mesothelioma risk following exposure to Anthophyllite and transitional fibers in humans is a consequencel of these microstructural features that appear to differentiate them from the equidimensional monoclinic forms of amphibole asbestos such as South African crocidolite and amosite.

  • Anthophyllite asbestos the role of fiber width in mesothelioma induction part 3 studies of american and japanese Anthophyllite asbestos additional supportive evidence
    Environment and Pollution, 2018
    Co-Authors: Edward B Ilgren, John A Hoskins

    Abstract:

    The largest anthopyllite deposits in the world are found in Finland and it is from here that most of the commercial Anthophyllite derives. However, other large deposits exist in both North America and Japan. Commercial production has existed in both these countries although not on a scale which matches the Finnish mines. Small deposits are known from several other countries but, apart from minor exploitation in India no significant mining has taken place. The North American deposits are primarily in the Eastern US states, mostly Maryland, Georgia and North Carolina although there was also extensive exploration in Alabama. In Japan, the major mining site was at Matsubase on the southermost island of Kyushu. Although these mines and attendant commercial concerns operated for decades and under conditions of high dust exposure no mesothelioma clusters are known from the mining areas.

  • Anthophyllite asbestos the role of fiber width in mesothelioma induction part 2 further epidemiological studies of occupational domestic and environmental exposure to finnish Anthophyllite asbestos
    Environment and Pollution, 2018
    Co-Authors: Edward B Ilgren, John A Hoskins

    Abstract:

    Although people in all sectors of the Finnish Anthophyllite industry, including their families, have been heavily exposed to Anthophyllite there is no evidence for even a single proven case of attributable mesothelioma. A few cases have been claimed but the evidence either, that they were mesotheliomas or that amphibole exposure was solely to Anthophyllite is, in every case examined, insufficient. Even among the population who lived in Karelia in Central Finland who were exposed domestically or enviromentally to Anthophyllite released during agricultural and various domestic activities and during transport from the mines, Finnish epidemiology found no risk of mesothelioma. There is also an absence of mesotheliomas reported in the earlier Finnish literature. This anomaly compared to the effects of exposure to other amphiboles is strong support for the role of fiber width in mesothelioma production. Anthophyllite, though, is not without clinical effect. As screening techniques improved it was discovered that of every person over the age of 65 years, one third living in Karelia had bilateral pleural plaques. The area was henceforth called the Endemic Pleural Plaque (EPP) zone. Radiographic analysis of the residents living in the district of Kuusjarvi led to suggestions that the cases resulted from asbestos blown from the Paakila facility via fiber drift as far away as 30 km. Later studies showed that ‘fiber drift’ was very unlikely to be a factor in the radiological findings thus observed.

E B Ilgren – 3rd expert on this subject based on the ideXlab platform

  • reply to the readership regarding ilgren hoskins 2018 Anthophyllite mesothelioma articles
    Environment and Pollution, 2019
    Co-Authors: E B Ilgren

    Abstract:

    Reply to the Readership regarding Ilgren & Hoskins (2018) Anthophyllite Mesothelioma Articles.

  • Reply to the Readership regarding Ilgren & Hoskins (2018) Anthophyllite Mesothelioma Articles
    Environment and Pollution, 2019
    Co-Authors: E B Ilgren

    Abstract:

    Reply to the Readership regarding Ilgren & Hoskins (2018) Anthophyllite Mesothelioma Articles.